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SWEDEN - 1941 MAURITANIA UPU SPECIMENS for the 1941 5kr blue Royal Palace, SG 250, in a vertical strip of three affixed to a small piece of archive sheet, approx size 65 x 80mm, these cancelled with red three-line 'SPECIMEN / COLLECTION / MAURITANIA' handstamps. A unique item from the Mauritania Post Office UPU collection. (3 stamps)